• Progress in Medical Physics
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• v.13 no.3
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• pp.129-134
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• 2002

The radiosurgery is planned that prescribed dose was irradiated to tumor for obtaining expected remedial value in stereotactic radiosurgery. The planning for many irregular tumor shape requires long computation time and skilled planners. Due to the rapid development in computer power recently, many optimization methods using computer has been proposed, although the practical method is still trial and error type of plan. In this study, many beam variables were considered and many tumor shapes were assumed cylinderical ideal models. Then, beam variables that covered the target within 50％ isodose curve were searched, the result was compared and analysed. The beam variables considered were isocenter separation distance, number of isocenters and collimator size. Dose distributions obtained with these variables were analysed by dose volume histogram(DVH) and dose profile at orthogonal plane. According to the results compared, the use of more isocenters than specified isocenter dosen't improve DVH and dose profile but only increases complexity of plan. The best result of DVH and dose profile are obtainedwhen isocenter separation was 1.0-1.2 in using same number of isocenter.

• Progress in Medical Physics
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• v.23 no.2
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• pp.106-113
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• 2012

The purpose of this study is to evaluate the variation of radiation dose distribution for liver tumor located in liver dome and for the interest organs(normal liver, kidney, stomach) with the pencil beam convolution (PBC) algorithm versus anisotropic Analyticalal algorithm (AAA) of the Varian Eclipse treatment planning system, The target volumes from 20 liver cancer patients were used to create treatment plans. Treatment plans for 10 patients were performed in Stereotactic Body Radiation Therapy (SBRT) plan and others were performed in 3 Dimensional Conformal Radiation Therapy (3DCRT) plan. dose calculation was recalculated by AAA algorithm after dose calculation was performed by PBC algorithm for 20 patients. Plans were optimized to 100% of the PTV by the Prescription Isodose in Dose Calculation with the PBC algorithm. Plans were recalculated with the AAA, retaining identical beam arrangements, monitor units, field weighting and collimator condition. In this study, Total PTV was to be statistically significant (SRS: p=0.018, 3DCRT: p=0.006) between PBC and AAA algorithm. and in the case of PTV, ITV in liver dome, plans for 3DCRT were to be statistically significant respectively (p=0.013, p=0.024). normal liver and kidney were to be statistically significant (p=0.009, p=0.037). For the predictive index of dose variation, CVF ratio was to be statistically significant for PTV in the liver dome versus PTV (SRS r=0.684, 3DCRT r=0.732, p<0.01) and CVF ratio for Tumor size was to be statistically significant (SRS r=-0.193, p=0.017, 3DCRT r=0.237, p=0.023).

• Radiation Oncology Journal
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• v.11 no.2
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• pp.439-448
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• 1993

The B-type gamma knife unit was installed at Kyung-Hee University Hospital in March 1992. The selective beam plugging method can be used to reduce the low percentage isodose profiles of normal sensitive organ and to modify the isodose curves of treatment volume for better shaping of the target volume. For representing the changes of the low percentage isodose profiles, the variations of dose distribution for several cases were discussed in this paper. The film dosimetry was peformed for the evaluation of calculated isodose profiles predicted by KULA dose planning system. The results were verified by RFA-3 automatic densitometry. The clinical application of selective beam shielding method was peformed in 17 patients in 100 patients who have undergone gamma knife radiosurgery for a year. The calculated and the measured isodose profiles for the high percentage regions were well consistent with each other. When the target of pituitary tumor is macro-size, the selective beam shielding method is the most applicable method. When the target size, however, is small, the correct selection of the proper helmet size is very important. All patients were exposed almost about 3~12 Gy for brain stem, and 3~11.2 Gy for optic apparatus. It is recommended that the same or other plugging patterns with multiple isocenters should be used for protection of the radiosensitive normal structures with precise treatment of CNS lesions.

• Progress in Medical Physics
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• v.24 no.4
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• pp.290-294
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• 2013

Stereotactic Radiosurgery require high accuracy and precision of patient positioning and target localization. We evaluate the real time positioning accuracy of isocenter using optic guided patient positioning system, ExacTrac (BrainLab, Germany), during spinal radiosurgery procedure. The system is based on real time detect multiple body markers attached on the selected patient skin landmarks. And a custom designed patient positioning verification tool (PPVT) was used to check the patient alignment and correct the patient repositioning before radiosurgery. In this study, We investigate the selected 8 metastatic spinal tumor cases. All type of tumors commonly closed to thoracic spinal code. To evaluate the isocenter positioning, real time patient alignment and positioning monitoring was carried out for comparing the current 3-dimensional position of markers with those of an initial reference positions. For a selected patient case, we have check the isocenter positioning per every 20 millisecond for 45 seconds during spinal radiosurgery. In this study, real time average isocenter positioning translation were $0.07{\pm}0.17$ mm, $0.11{\pm}0.18$ mm, $0.13{\pm}0.26$ mm, and $0.20{\pm}0.37$ mm in the x (lateral), y (longitudinal), z (vertical) directions and mean spatial error, respectively. And body rotations were $0.14{\pm}0.07^{\circ}$, $0.11{\pm}0.07^{\circ}$, $0.03{\pm}0.04^{\circ}$ in longitudinal, lateral, table directions and mean body rotation $0.20{\pm}0.11^{\circ}$, respectively. In this study, the maximum mean deviation of real time isocenter positioning translation during spinal radiosurgery was acceptable accuracy clinically.

• Radiation Oncology Journal
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• v.11 no.2
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• pp.241-247
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• 1993

Between July 1988 and December 1992, we treated 45 patients who had deep seated inoperable or residual and/or recurrent intracranial tumors using LINAC based stereotactic radiosurgery at the Department of Therapeutic Radiology, Kangnam St. Mary's Hospital, Catholic University Medical College. Treated intracranial tumors included pituitary tumors (n=15), acoustic neurinomas (n=8), meningiomas (n=7), gliomas (n=6), craniopharyngiomas (n=4), pinealomas (n=3), hemangioblastomas (n=2), and solitary metastatic tumor from lung cancer (n=1). The dimension of treatment field varied from 0.23 to 42.88 $cm^3\;(mean;\;7.26\;cm^3)$. The maximum tumor doses ranging from 5 to 35.5 Gy (mean; 29.9 Gy) were given, and depended on patients' age, target volume, location of lesion and previous history of irradiation. There were 22 male and 23 female patients. The age was varied from 5 to 74 years of age (a median age; 43 years). The mean duration of follow-up was 35 months (2~55 months). To date, 18 $(39.1\%)$ of 46 intracranial tumors treated with SRS showed absent or decrease of the tumor by serial follow-up CT and/or MRI and 16 $(34.8\%)$ were stationary, e.g. growth arrest. From the view point of the clinical aspects, 34 $(73.9\%)$ of 46 tumors were considered improved status, that is, alive with no evidence of active tumor and 8 $(17.4\%)$ of them were stable, alive with disease but no deterioration as compared with before SRS. Although there showed slight increase of the tumor in size according to follow-up imagings of 4 cases (pituitary tumor 1, acoustic neurinomas 2, pinealoma 1), they still represented clinically stable status. Clinically, two $(4.4\%)$ Patients who were anaplastic astrocytoma (n=1) and metastatic brain tumor (n=1) were worsened following SRS treatment. So far, no serious complications were found after treatment. The minor degree headache which could be relieved by steroid or analgesics and transient focal hair loss were observed in a few cases. There should be meticulous long term follow-up inall cases.

• Radiation Oncology Journal
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• v.21 no.2
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• pp.107-111
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• 2003

Purpose: To establish the role of stereoactic radiosurgery using a linear accelerator for the treatment of patients with cavernous angloma. Materials and Methods: Between February 1995 and May 1997, 11 patients with cavernous angioma were treated with stereotactic radiosurgery using a linear accelerator. Diagnoses were based on the magnetic resonance imaging in 8 patients, and the histological in 3. The vascular lesions were located on the brainstem (5 cases), cerebellum (2 cases) thalamus (1 case) and cerebrum (3 cases). The clinical presentation at onset included previous intracerebral hemorrhages (9 cases) and seizures (2 cases). All patients were treated with a a linac-based radiosurgery. The median dose of radiation delivered was 16 Gy ranging from 14 to 24 Gy, which was typically proscribed to the 80$\%$ isodose surface (range 50 $\~$ 80$\%$), corresponding to the periphery of the lesion with a single isocenter. Ten patients were followed-up. Results: The median follow-up was 49 months ranging from 8 to 73 months, during which time two patients developed an intracerebral hemorrhage, 1 at 8 months, with the other at 64 months post radiosurgery. One patient developed neurological deficit after radiosurgery, and two developed an edema on the T2 weighted images of the MRI surrounding the radiosurgical target. Conclusion: The use of stereotactic radiosurgery in the treatment of a cavernous angioma may be effective in the prevention of rebleedlng, and can be safely delivered. However, a longer follow-up period will be required.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.1
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• pp.59-67
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• 2014

Purpose : This study aims to evaluate 3D dosimetric impact for MIP image and each phase image in stereotactic body radiotherapy (SBRT) for lung cancer using volumetric modulated arc therapy (VMAT). Materials and Methods : For each of 5 patients with non-small-cell pulmonary tumors, a respiration-correlated four-dimensional computed tomography (4DCT) study was performed. We obtain ten 3D CT images corresponding to phases of a breathing cycle. Treatment plans were generated using MIP CT image and each phases 3D CT. We performed the dose verification of the TPS with use of the Ion chamber and COMPASS. The dose distribution that were 3D reconstructed using MIP CT image compared with dose distribution on the corresponding phase of the 4D CT data. Results : Gamma evaluation was performed to evaluate the accuracy of dose delivery for MIP CT data and 4D CT data of 5 patients. The average percentage of points passing the gamma criteria of 2 mm/2% about 99%. The average Homogeneity Index difference between MIP and each 3D data of patient dose was 0.03~0.04. The average difference between PTV maximum dose was 3.30 cGy, The average different Spinal Coad dose was 3.30 cGy, The average of difference with $V_{20}$, $V_{10}$, $V_5$ of Lung was -0.04%~2.32%. The average Homogeneity Index difference between MIP and each phase 3d data of all patient was -0.03~0.03. The average PTV maximum dose difference was minimum for 10% phase and maximum for 70% phase. The average Spain cord maximum dose difference was minimum for 0% phase and maximum for 50% phase. The average difference of $V_{20}$, $V_{10}$, $V_5$ of Lung show bo certain trend. Conclusion : There is no tendency of dose difference between MIP with 3D CT data of each phase. But there are appreciable difference for specific phase. It is need to study about patient group which has similar tumor location and breathing motion. Then we compare with dose distribution for each phase 3D image data or MIP image data. we will determine appropriate image data for treatment plan.

• Progress in Medical Physics
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• v.29 no.2
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• pp.53-58
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• 2018

This paper evaluates patient-specific quality assurance (PSQA) in the treatment of small and multiple tumors by the CyberKnife system with fixed collimators, using an ion chamber and EBT3 films. We selected 49 patients with single or multiple brain tumors, and the treatment plans include one to four targets with total volumes ranging from 0.12 cc to 3.74 cc. All PSQA deliveries were performed with a stereotactic dose verification phantom. The A16 microchamber (Standard Imaging, WI, USA) and Gafchromic EBT3 film (Ashland ISP Advanced Materials, NJ, USA) were inserted into the phantom to measure the point dose of the target and the dose distribution, respectively. The film was scanned 1 hr after irradiation by a film digitizer scanner and analyzed using RIT software (Radiological Imaging Technology, CO, USA). The acceptance criteria was <5% for the point dose measurement and >90% gamma passing rate using 3%/3 mm and relative dose difference, respectively. The point dose errors between the calculated and measured dose by the ion chamber were in the range of -17.5% to 8.03%. The mean point dose differences for 5 mm, 7.5 mm, and 10 mm fixed cone size was -11.1%, -4.1%, and -1.5%, respectively. The mean gamma passing rates for all cases was 96.1%. Although the maximum dose distribution of multiple targets was not shown in the film, gamma distribution showed that dose verification for multiple tumors can be performed. The use of the microchamber and EBT3 film made it possible to verify the dosimetric and mechanical accuracy of small and multiple targets. In particular, the correction factors should be applied to small fixed collimators less than 10 mm.

• Journal of Korean Neurosurgical Society
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• v.41 no.6
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• pp.359-366
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• 2007

Trigeminal neuralgia is a condition associated with severe episodic lancinating facial pain subject to remissions and relapses. Trigeminal neuralgia is often associated with blood vessel cross compression of the root entry zone or more rarely with demyelinating diseases and occasionally with direct compression by neoplasms of the posterior fossa. If initial medical management fails to control pain or is associated with unacceptable side effects, a variety of surgical procedures offer the hope for long-lasting pain relief or even cure. For patients who are healthy without significant medical co-morbidities, direct microsurgical vascular decompression [MVD] offers treatment that is often definitive. Other surgical options are effective for elderly patients not suitable for MVD. Percutaneous retrogasserian glycerol rhizotomy is a minimally invasive technique that is based on anatomic definition of the trigeminal cistern followed by injection of anhydrous glycerol to produce a weak neurolytic effect on the post-ganglionic fibers. Other percutaneous management strategies include radiofrequency rhizotomy and balloon compression. More recently, stereotactic radiosurgery has been used as a truly minimally invasive strategy. It also is anatomically based using high resolution MRI to define the retrogasserian target. Radiosurgery provides effective symptomatic relief in the vast majority of patients, especially those who have never had prior surgical procedures. For younger patients, we recommend microvascular decompression. For patients with severe exacerbations of their pain and who need rapid response to treatment, we suggest glycerol rhizotomy. For other patients, gamma knife radiosurgery represents an effective management strategy with excellent preservation of existing facial sensation.

• Journal of Korean Neurosurgical Society
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• v.55 no.3
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• pp.131-135
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• 2014

Objective : With the growing interests of bacteria as a targeting vector for cancer treatment, diverse genetically engineered Salmonella has been reported to be capable of targeting primary or metastatic tumor regions after intravenous injection into mouse tumor models. The purpose of this study was to investigate the capability of the genetically engineered Salmonella typhimurium (S. typhimurium) to access the glioma xenograft, which was monitored in mouse brain tumor models using optical bioluminescence imaging technique. Methods : U87 malignant glioma cells (U87-MG) stably transfected with firefly luciferase (Fluc) were implanted into BALB/cAnN nude mice by stereotactic injection into the striatum. After tumor formation, attenuated S. typhimurium expressing bacterial luciferase (Lux) was injected into the tail vein. Bioluminescence signals from transfected cells or bacteria were monitored using a cooled charge-coupled device camera to identify the tumor location or to trace the bacterial migration. Immunofluorescence staining was also performed in frozen sections of mouse glioma xenograft. Results : The injected S. typhimurium exclusively localized in the glioma xenograft region of U87-MG-bearing mouse. Immunofluorescence staining also demonstrated the accumulation of S. typhimurium in the brain tumors. Conclusion : The present study demonstrated that S. typhimurium can target glioma xenograft, and may provide a potentially therapeutic probe for glioma.